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diff --git a/share/man/man4/ddb.4 b/share/man/man4/ddb.4 new file mode 100644 index 0000000..01f5135 --- /dev/null +++ b/share/man/man4/ddb.4 @@ -0,0 +1,1468 @@ +.\" +.\" Mach Operating System +.\" Copyright (c) 1991,1990 Carnegie Mellon University +.\" Copyright (c) 2007 Robert N. M. Watson +.\" All Rights Reserved. +.\" +.\" Permission to use, copy, modify and distribute this software and its +.\" documentation is hereby granted, provided that both the copyright +.\" notice and this permission notice appear in all copies of the +.\" software, derivative works or modified versions, and any portions +.\" thereof, and that both notices appear in supporting documentation. +.\" +.\" CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" +.\" CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR +.\" ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. +.\" +.\" Carnegie Mellon requests users of this software to return to +.\" +.\" Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU +.\" School of Computer Science +.\" Carnegie Mellon University +.\" Pittsburgh PA 15213-3890 +.\" +.\" any improvements or extensions that they make and grant Carnegie Mellon +.\" the rights to redistribute these changes. +.\" +.\" changed a \# to #, since groff choked on it. +.\" +.\" HISTORY +.\" ddb.4,v +.\" Revision 1.1 1993/07/15 18:41:02 brezak +.\" Man page for DDB +.\" +.\" Revision 2.6 92/04/08 08:52:57 rpd +.\" Changes from OSF. +.\" [92/01/17 14:19:22 jsb] +.\" Changes for OSF debugger modifications. +.\" [91/12/12 tak] +.\" +.\" Revision 2.5 91/06/25 13:50:22 rpd +.\" Added some watchpoint explanation. +.\" [91/06/25 rpd] +.\" +.\" Revision 2.4 91/06/17 15:47:31 jsb +.\" Added documentation for continue/c, match, search, and watchpoints. +.\" I've not actually explained what a watchpoint is; maybe Rich can +.\" do that (hint, hint). +.\" [91/06/17 10:58:08 jsb] +.\" +.\" Revision 2.3 91/05/14 17:04:23 mrt +.\" Correcting copyright +.\" +.\" Revision 2.2 91/02/14 14:10:06 mrt +.\" Changed to new Mach copyright +.\" [91/02/12 18:10:12 mrt] +.\" +.\" Revision 2.2 90/08/30 14:23:15 dbg +.\" Created. +.\" [90/08/30 dbg] +.\" +.\" $FreeBSD$ +.\" +.Dd September 30, 2013 +.Dt DDB 4 +.Os +.Sh NAME +.Nm ddb +.Nd interactive kernel debugger +.Sh SYNOPSIS +In order to enable kernel debugging facilities include: +.Bd -ragged -offset indent +.Cd options KDB +.Cd options DDB +.Ed +.Pp +To prevent activation of the debugger on kernel +.Xr panic 9 : +.Bd -ragged -offset indent +.Cd options KDB_UNATTENDED +.Ed +.Pp +In order to print a stack trace of the current thread on the console +for a panic: +.Bd -ragged -offset indent +.Cd options KDB_TRACE +.Ed +.Pp +To print the numerical value of symbols in addition to the symbolic +representation, define: +.Bd -ragged -offset indent +.Cd options DDB_NUMSYM +.Ed +.Pp +To enable the +.Xr gdb 1 +backend, so that remote debugging with +.Xr kgdb 1 +is possible, include: +.Bd -ragged -offset indent +.Cd options GDB +.Ed +.Sh DESCRIPTION +The +.Nm +kernel debugger is an interactive debugger with a syntax inspired by +.Xr gdb 1 . +If linked into the running kernel, +it can be invoked locally with the +.Ql debug +.Xr keymap 5 +action. +The debugger is also invoked on kernel +.Xr panic 9 +if the +.Va debug.debugger_on_panic +.Xr sysctl 8 +MIB variable is set non-zero, +which is the default +unless the +.Dv KDB_UNATTENDED +option is specified. +.Pp +The current location is called +.Va dot . +The +.Va dot +is displayed with +a hexadecimal format at a prompt. +The commands +.Ic examine +and +.Ic write +update +.Va dot +to the address of the last line +examined or the last location modified, and set +.Va next +to the address of +the next location to be examined or changed. +Other commands do not change +.Va dot , +and set +.Va next +to be the same as +.Va dot . +.Pp +The general command syntax is: +.Ar command Ns Op Li / Ns Ar modifier +.Ar address Ns Op Li , Ns Ar count +.Pp +A blank line repeats the previous command from the address +.Va next +with +count 1 and no modifiers. +Specifying +.Ar address +sets +.Va dot +to the address. +Omitting +.Ar address +uses +.Va dot . +A missing +.Ar count +is taken +to be 1 for printing commands or infinity for stack traces. +.Pp +The +.Nm +debugger has a pager feature (like the +.Xr more 1 +command) +for the output. +If an output line exceeds the number set in the +.Va lines +variable, it displays +.Dq Li --More-- +and waits for a response. +The valid responses for it are: +.Pp +.Bl -tag -compact -width ".Li SPC" +.It Li SPC +one more page +.It Li RET +one more line +.It Li q +abort the current command, and return to the command input mode +.El +.Pp +Finally, +.Nm +provides a small (currently 10 items) command history, and offers +simple +.Nm emacs Ns -style +command line editing capabilities. +In addition to +the +.Nm emacs +control keys, the usual +.Tn ANSI +arrow keys may be used to +browse through the history buffer, and move the cursor within the +current line. +.Sh COMMANDS +.Bl -tag -width indent -compact +.It Ic examine +.It Ic x +Display the addressed locations according to the formats in the modifier. +Multiple modifier formats display multiple locations. +If no format is specified, the last format specified for this command +is used. +.Pp +The format characters are: +.Bl -tag -compact -width indent +.It Cm b +look at by bytes (8 bits) +.It Cm h +look at by half words (16 bits) +.It Cm l +look at by long words (32 bits) +.It Cm g +look at by quad words (64 bits) +.It Cm a +print the location being displayed +.It Cm A +print the location with a line number if possible +.It Cm x +display in unsigned hex +.It Cm z +display in signed hex +.It Cm o +display in unsigned octal +.It Cm d +display in signed decimal +.It Cm u +display in unsigned decimal +.It Cm r +display in current radix, signed +.It Cm c +display low 8 bits as a character. +Non-printing characters are displayed as an octal escape code (e.g., +.Ql \e000 ) . +.It Cm s +display the null-terminated string at the location. +Non-printing characters are displayed as octal escapes. +.It Cm m +display in unsigned hex with character dump at the end of each line. +The location is also displayed in hex at the beginning of each line. +.It Cm i +display as an instruction +.It Cm I +display as an instruction with possible alternate formats depending on the +machine, but none of the supported architectures have an alternate format. +.It Cm S +display a symbol name for the pointer stored at the address +.El +.Pp +.It Ic xf +Examine forward: +execute an +.Ic examine +command with the last specified parameters to it +except that the next address displayed by it is used as the start address. +.Pp +.It Ic xb +Examine backward: +execute an +.Ic examine +command with the last specified parameters to it +except that the last start address subtracted by the size displayed by it +is used as the start address. +.Pp +.It Ic print Ns Op Li / Ns Cm acdoruxz +.It Ic p Ns Op Li / Ns Cm acdoruxz +Print +.Ar addr Ns s +according to the modifier character (as described above for +.Cm examine ) . +Valid formats are: +.Cm a , x , z , o , d , u , r , +and +.Cm c . +If no modifier is specified, the last one specified to it is used. +The argument +.Ar addr +can be a string, in which case it is printed as it is. +For example: +.Bd -literal -offset indent +print/x "eax = " $eax "\enecx = " $ecx "\en" +.Ed +.Pp +will print like: +.Bd -literal -offset indent +eax = xxxxxx +ecx = yyyyyy +.Ed +.Pp +.It Xo +.Ic write Ns Op Li / Ns Cm bhl +.Ar addr expr1 Op Ar expr2 ... +.Xc +.It Xo +.Ic w Ns Op Li / Ns Cm bhl +.Ar addr expr1 Op Ar expr2 ... +.Xc +Write the expressions specified after +.Ar addr +on the command line at succeeding locations starting with +.Ar addr . +The write unit size can be specified in the modifier with a letter +.Cm b +(byte), +.Cm h +(half word) or +.Cm l +(long word) respectively. +If omitted, +long word is assumed. +.Pp +.Sy Warning : +since there is no delimiter between expressions, strange +things may happen. +It is best to enclose each expression in parentheses. +.Pp +.It Ic set Li $ Ns Ar variable Oo Li = Oc Ar expr +Set the named variable or register with the value of +.Ar expr . +Valid variable names are described below. +.Pp +.It Ic break Ns Op Li / Ns Cm u +.It Ic b Ns Op Li / Ns Cm u +Set a break point at +.Ar addr . +If +.Ar count +is supplied, continues +.Ar count +\- 1 times before stopping at the +break point. +If the break point is set, a break point number is +printed with +.Ql # . +This number can be used in deleting the break point +or adding conditions to it. +.Pp +If the +.Cm u +modifier is specified, this command sets a break point in user +address space. +Without the +.Cm u +option, the address is considered to be in the kernel +space, and a wrong space address is rejected with an error message. +This modifier can be used only if it is supported by machine dependent +routines. +.Pp +.Sy Warning : +If a user text is shadowed by a normal user space debugger, +user space break points may not work correctly. +Setting a break +point at the low-level code paths may also cause strange behavior. +.Pp +.It Ic delete Ar addr +.It Ic d Ar addr +.It Ic delete Li # Ns Ar number +.It Ic d Li # Ns Ar number +Delete the break point. +The target break point can be specified by a +break point number with +.Ql # , +or by using the same +.Ar addr +specified in the original +.Ic break +command. +.Pp +.It Ic watch Ar addr Ns Li , Ns Ar size +Set a watchpoint for a region. +Execution stops when an attempt to modify the region occurs. +The +.Ar size +argument defaults to 4. +If you specify a wrong space address, the request is rejected +with an error message. +.Pp +.Sy Warning : +Attempts to watch wired kernel memory +may cause unrecoverable error in some systems such as i386. +Watchpoints on user addresses work best. +.Pp +.It Ic hwatch Ar addr Ns Li , Ns Ar size +Set a hardware watchpoint for a region if supported by the +architecture. +Execution stops when an attempt to modify the region occurs. +The +.Ar size +argument defaults to 4. +.Pp +.Sy Warning : +The hardware debug facilities do not have a concept of separate +address spaces like the watch command does. +Use +.Ic hwatch +for setting watchpoints on kernel address locations only, and avoid +its use on user mode address spaces. +.Pp +.It Ic dhwatch Ar addr Ns Li , Ns Ar size +Delete specified hardware watchpoint. +.Pp +.It Ic step Ns Op Li / Ns Cm p +.It Ic s Ns Op Li / Ns Cm p +Single step +.Ar count +times (the comma is a mandatory part of the syntax). +If the +.Cm p +modifier is specified, print each instruction at each step. +Otherwise, only print the last instruction. +.Pp +.Sy Warning : +depending on machine type, it may not be possible to +single-step through some low-level code paths or user space code. +On machines with software-emulated single-stepping (e.g., pmax), +stepping through code executed by interrupt handlers will probably +do the wrong thing. +.Pp +.It Ic continue Ns Op Li / Ns Cm c +.It Ic c Ns Op Li / Ns Cm c +Continue execution until a breakpoint or watchpoint. +If the +.Cm c +modifier is specified, count instructions while executing. +Some machines (e.g., pmax) also count loads and stores. +.Pp +.Sy Warning : +when counting, the debugger is really silently single-stepping. +This means that single-stepping on low-level code may cause strange +behavior. +.Pp +.It Ic until Ns Op Li / Ns Cm p +Stop at the next call or return instruction. +If the +.Cm p +modifier is specified, print the call nesting depth and the +cumulative instruction count at each call or return. +Otherwise, +only print when the matching return is hit. +.Pp +.It Ic next Ns Op Li / Ns Cm p +.It Ic match Ns Op Li / Ns Cm p +Stop at the matching return instruction. +If the +.Cm p +modifier is specified, print the call nesting depth and the +cumulative instruction count at each call or return. +Otherwise, only print when the matching return is hit. +.Pp +.It Xo +.Ic trace Ns Op Li / Ns Cm u +.Op Ar pid | tid +.Op Li , Ns Ar count +.Xc +.It Xo +.Ic t Ns Op Li / Ns Cm u +.Op Ar pid | tid +.Op Li , Ns Ar count +.Xc +.It Xo +.Ic where Ns Op Li / Ns Cm u +.Op Ar pid | tid +.Op Li , Ns Ar count +.Xc +.It Xo +.Ic bt Ns Op Li / Ns Cm u +.Op Ar pid | tid +.Op Li , Ns Ar count +.Xc +Stack trace. +The +.Cm u +option traces user space; if omitted, +.Ic trace +only traces +kernel space. +The optional argument +.Ar count +is the number of frames to be traced. +If +.Ar count +is omitted, all frames are printed. +.Pp +.Sy Warning : +User space stack trace is valid +only if the machine dependent code supports it. +.Pp +.It Xo +.Ic search Ns Op Li / Ns Cm bhl +.Ar addr +.Ar value +.Op Ar mask +.Op Li , Ns Ar count +.Xc +Search memory for +.Ar value . +This command might fail in interesting +ways if it does not find the searched-for value. +This is because +.Nm +does not always recover from touching bad memory. +The optional +.Ar count +argument limits the search. +.\" +.Pp +.It Xo +.Ic findstack +.Ar addr +.Xc +Prints the thread address for a thread kernel-mode stack of which contains the +specified address. +If the thread is not found, search the thread stack cache and prints the +cached stack address. +Otherwise, prints nothing. +.Pp +.It Ic show Cm all procs Ns Op Li / Ns Cm m +.It Ic ps Ns Op Li / Ns Cm m +Display all process information. +The process information may not be shown if it is not +supported in the machine, or the bottom of the stack of the +target process is not in the main memory at that time. +The +.Cm m +modifier will alter the display to show VM map +addresses for the process and not show other information. +.\" +.Pp +.It Ic show Cm all ttys +Show all TTY's within the system. +Output is similar to +.Xr pstat 8 , +but also includes the address of the TTY structure. +.\" +.Pp +.It Ic show Cm allchains +Show the same information like "show lockchain" does, but +for every thread in the system. +.\" +.Pp +.It Ic show Cm alllocks +Show all locks that are currently held. +This command is only available if +.Xr witness 4 +is included in the kernel. +.\" +.Pp +.It Ic show Cm allpcpu +The same as "show pcpu", but for every CPU present in the system. +.\" +.Pp +.It Ic show Cm allrman +Show information related with resource management, including +interrupt request lines, DMA request lines, I/O ports and I/O memory +addresses. +.\" +.Pp +.It Ic show Cm apic +Dump data about APIC IDT vector mappings. +.\" +.Pp +.It Ic show Cm breaks +Show breakpoints set with the "break" command. +.\" +.Pp +.It Ic show Cm buffer +Show buffer structure of +.Vt struct buf +type. +Such a structure is used within the +.Fx +kernel for the I/O subsystem +implementation. +For an exact interpretation of the output, please see the +.Pa sys/buf.h +header file. +.\" +.Pp +.It Ic show Cm cbstat +Show brief information about the TTY subsystem. +.\" +.Pp +.It Ic show Cm cdev +Without argument, show the list of all created cdev's, consisting of devfs +node name and struct cdev address. +When address of cdev is supplied, show some internal devfs state of the cdev. +.\" +.Pp +.It Ic show Cm conifhk +Lists hooks currently waiting for completion in +run_interrupt_driven_config_hooks(). +.\" +.Pp +.It Ic show Cm cpusets +Print numbered root and assigned CPU affinity sets. +See +.Xr cpuset 2 +for more details. +.\" +.Pp +.It Ic show Cm cyrixreg +Show registers specific to the Cyrix processor. +.\" +.Pp +.It Ic show Cm domain Ar addr +Print protocol domain structure +.Vt struct domain +at address +.Ar addr . +See the +.Pa sys/domain.h +header file for more details on the exact meaning of the structure fields. +.\" +.Pp +.It Ic show Cm ffs Op Ar addr +Show brief information about ffs mount at the address +.Ar addr , +if argument is given. +Otherwise, provides the summary about each ffs mount. +.\" +.Pp +.It Ic show Cm file Ar addr +Show information about the file structure +.Vt struct file +present at address +.Ar addr . +.\" +.Pp +.It Ic show Cm files +Show information about every file structure in the system. +.\" +.Pp +.It Ic show Cm freepages +Show the number of physical pages in each of the free lists. +.\" +.Pp +.It Ic show Cm geom Op Ar addr +If the +.Ar addr +argument is not given, displays the entire GEOM topology. +If +.Ar addr +is given, displays details about the given GEOM object (class, geom, +provider or consumer). +.\" +.Pp +.It Ic show Cm idt +Show IDT layout. +The first column specifies the IDT vector. +The second one is the name of the interrupt/trap handler. +Those functions are machine dependent. +.\" +.Pp +.It Ic show Cm inodedeps Op Ar addr +Show brief information about each inodedep structure. +If +.Ar addr +is given, only inodedeps belonging to the fs located at the +supplied address are shown. +.\" +.Pp +.It Ic show Cm inpcb Ar addr +Show information on IP Control Block +.Vt struct in_pcb +present at +.Ar addr . +.\" +.Pp +.It Ic show Cm intr +Dump information about interrupt handlers. +.\" +.Pp +.It Ic show Cm intrcnt +Dump the interrupt statistics. +.\" +.Pp +.It Ic show Cm irqs +Show interrupt lines and their respective kernel threads. +.\" +.Pp +.It Ic show Cm jails +Show the list of +.Xr jail 8 +instances. +In addition to what +.Xr jls 8 +shows, also list kernel internal details. +.\" +.Pp +.It Ic show Cm lapic +Show information from the local APIC registers for this CPU. +.\" +.Pp +.It Ic show Cm lock Ar addr +Show lock structure. +The output format is as follows: +.Bl -tag -width "flags" +.It Ic class: +Class of the lock. +Possible types include +.Xr mutex 9 , +.Xr rmlock 9 , +.Xr rwlock 9 , +.Xr sx 9 . +.It Ic name: +Name of the lock. +.It Ic flags: +Flags passed to the lock initialization function. +For exact possibilities see manual pages of possible lock types. +.It Ic state: +Current state of a lock. +As well as +.Ic flags +it's lock-specific. +.It Ic owner: +Lock owner. +.El +.\" +.Pp +.It Ic show Cm lockchain Ar addr +Show all threads a particular thread at address +.Ar addr +is waiting on based on non-sleepable and non-spin locks. +.\" +.Pp +.It Ic show Cm lockedbufs +Show the same information as "show buf", but for every locked +.Vt struct buf +object. +.\" +.Pp +.It Ic show Cm lockedvnods +List all locked vnodes in the system. +.\" +.Pp +.It Ic show Cm locks +Prints all locks that are currently acquired. +This command is only available if +.Xr witness 4 +is included in the kernel. +.\" +.Pp +.It Ic show Cm locktree +.\" +.Pp +.It Ic show Cm malloc +Prints +.Xr malloc 9 +memory allocator statistics. +The output format is as follows: +.Pp +.Bl -tag -compact -offset indent -width "Requests" +.It Ic Type +Specifies a type of memory. +It is the same as a description string used while defining the +given memory type with +.Xr MALLOC_DECLARE 9 . +.It Ic InUse +Number of memory allocations of the given type, for which +.Xr free 9 +has not been called yet. +.It Ic MemUse +Total memory consumed by the given allocation type. +.It Ic Requests +Number of memory allocation requests for the given +memory type. +.El +.Pp +The same information can be gathered in userspace with +.Dq Nm vmstat Fl m . +.\" +.Pp +.It Ic show Cm map Ns Oo Li / Ns Cm f Oc Ar addr +Prints the VM map at +.Ar addr . +If the +.Cm f +modifier is specified the +complete map is printed. +.\" +.Pp +.It Ic show Cm msgbuf +Print the system's message buffer. +It is the same output as in the +.Dq Nm dmesg +case. +It is useful if you got a kernel panic, attached a serial cable +to the machine and want to get the boot messages from before the +system hang. +.\" +.It Ic show Cm mount +Displays short info about all currently mounted file systems. +.Pp +.It Ic show Cm mount Ar addr +Displays details about the given mount point. +.\" +.Pp +.It Ic show Cm object Ns Oo Li / Ns Cm f Oc Ar addr +Prints the VM object at +.Ar addr . +If the +.Cm f +option is specified the +complete object is printed. +.\" +.Pp +.It Ic show Cm page +Show statistics on VM pages. +.\" +.Pp +.It Ic show Cm pageq +Show statistics on VM page queues. +.\" +.Pp +.It Ic show Cm pciregs +Print PCI bus registers. +The same information can be gathered in userspace by running +.Dq Nm pciconf Fl lv . +.\" +.Pp +.It Ic show Cm pcpu +Print current processor state. +The output format is as follows: +.Pp +.Bl -tag -compact -offset indent -width "spin locks held:" +.It Ic cpuid +Processor identifier. +.It Ic curthread +Thread pointer, process identifier and the name of the process. +.It Ic curpcb +Control block pointer. +.It Ic fpcurthread +FPU thread pointer. +.It Ic idlethread +Idle thread pointer. +.It Ic APIC ID +CPU identifier coming from APIC. +.It Ic currentldt +LDT pointer. +.It Ic spin locks held +Names of spin locks held. +.El +.\" +.Pp +.It Ic show Cm pgrpdump +Dump process groups present within the system. +.\" +.Pp +.It Ic show Cm proc Op Ar addr +If no +.Op Ar addr +is specified, print information about the current process. +Otherwise, show information about the process at address +.Ar addr . +.\" +.Pp +.It Ic show Cm procvm +Show process virtual memory layout. +.\" +.Pp +.It Ic show Cm protosw Ar addr +Print protocol switch structure +.Vt struct protosw +at address +.Ar addr . +.\" +.Pp +.It Ic show Cm registers Ns Op Li / Ns Cm u +Display the register set. +If the +.Cm u +modifier is specified, it displays user registers instead of +kernel registers or the currently saved one. +.Pp +.Sy Warning : +The support of the +.Cm u +modifier depends on the machine. +If not supported, incorrect information will be displayed. +.\" +.Pp +.It Ic show Cm rman Ar addr +Show resource manager object +.Vt struct rman +at address +.Ar addr . +Addresses of particular pointers can be gathered with "show allrman" +command. +.\" +.Pp +.It Ic show Cm rtc +Show real time clock value. +Useful for long debugging sessions. +.\" +.Pp +.It Ic show Cm sleepchain +Show all the threads a particular thread is waiting on based on +sleepable locks. +.\" +.Pp +.It Ic show Cm sleepq +.It Ic show Cm sleepqueue +Both commands provide the same functionality. +They show sleepqueue +.Vt struct sleepqueue +structure. +Sleepqueues are used within the +.Fx +kernel to implement sleepable +synchronization primitives (thread holding a lock might sleep or +be context switched), which at the time of writing are: +.Xr condvar 9 , +.Xr sx 9 +and standard +.Xr msleep 9 +interface. +.\" +.Pp +.It Ic show Cm sockbuf Ar addr +.It Ic show Cm socket Ar addr +Those commands print +.Vt struct sockbuf +and +.Vt struct socket +objects placed at +.Ar addr . +Output consists of all values present in structures mentioned. +For exact interpretation and more details, visit +.Pa sys/socket.h +header file. +.\" +.Pp +.It Ic show Cm sysregs +Show system registers (e.g., +.Li cr0-4 +on i386.) +Not present on some platforms. +.\" +.Pp +.It Ic show Cm tcpcb Ar addr +Print TCP control block +.Vt struct tcpcb +lying at address +.Ar addr . +For exact interpretation of output, visit +.Pa netinet/tcp.h +header file. +.\" +.Pp +.It Ic show Cm thread Op Ar addr +If no +.Ar addr +is specified, show detailed information about current thread. +Otherwise, information about thread at +.Ar addr +is printed. +.\" +.Pp +.It Ic show Cm threads +Show all threads within the system. +Output format is as follows: +.Pp +.Bl -tag -compact -offset indent -width "Second column" +.It Ic First column +Thread identifier (TID) +.It Ic Second column +Thread structure address +.It Ic Third column +Backtrace. +.El +.\" +.Pp +.It Ic show Cm tty Ar addr +Display the contents of a TTY structure in a readable form. +.\" +.Pp +.It Ic show Cm turnstile Ar addr +Show turnstile +.Vt struct turnstile +structure at address +.Ar addr . +Turnstiles are structures used within the +.Fx +kernel to implement +synchronization primitives which, while holding a specific type of lock, cannot +sleep or context switch to another thread. +Currently, those are: +.Xr mutex 9 , +.Xr rwlock 9 , +.Xr rmlock 9 . +.\" +.Pp +.It Ic show Cm uma +Show UMA allocator statistics. +Output consists five columns: +.Pp +.Bl -tag -compact -offset indent -width "Requests" +.It Cm "Zone" +Name of the UMA zone. +The same string that was passed to +.Xr uma_zcreate 9 +as a first argument. +.It Cm "Size" +Size of a given memory object (slab). +.It Cm "Used" +Number of slabs being currently used. +.It Cm "Free" +Number of free slabs within the UMA zone. +.It Cm "Requests" +Number of allocations requests to the given zone. +.El +.Pp +The very same information might be gathered in the userspace +with the help of +.Dq Nm vmstat Fl z . +.\" +.Pp +.It Ic show Cm unpcb Ar addr +Shows UNIX domain socket private control block +.Vt struct unpcb +present at the address +.Ar addr . +.\" +.Pp +.It Ic show Cm vmochk +Prints, whether the internal VM objects are in a map somewhere +and none have zero ref counts. +.\" +.Pp +.It Ic show Cm vmopag +This is supposed to show physical addresses consumed by a +VM object. +Currently, it is not possible to use this command when +.Xr witness 4 +is compiled in the kernel. +.\" +.Pp +.It Ic show Cm vnode Op Ar addr +Prints vnode +.Vt struct vnode +structure lying at +.Op Ar addr . +For the exact interpretation of the output, look at the +.Pa sys/vnode.h +header file. +.\" +.Pp +.It Ic show Cm vnodebufs Ar addr +Shows clean/dirty buffer lists of the vnode located at +.Ar addr . +.\" +.Pp +.It Ic show Cm watches +Displays all watchpoints. +Shows watchpoints set with "watch" command. +.\" +.Pp +.It Ic show Cm witness +Shows information about lock acquisition coming from the +.Xr witness 4 +subsystem. +.\" +.Pp +.It Ic gdb +Toggles between remote GDB and DDB mode. +In remote GDB mode, another machine is required that runs +.Xr gdb 1 +using the remote debug feature, with a connection to the serial +console port on the target machine. +Currently only available on the +i386 +architecture. +.Pp +.It Ic halt +Halt the system. +.Pp +.It Ic kill Ar sig pid +Send signal +.Ar sig +to process +.Ar pid . +The signal is acted on upon returning from the debugger. +This command can be used to kill a process causing resource contention +in the case of a hung system. +See +.Xr signal 3 +for a list of signals. +Note that the arguments are reversed relative to +.Xr kill 2 . +.Pp +.It Ic reboot Op Ar seconds +.It Ic reset Op Ar seconds +Hard reset the system. +If the optional argument +.Ar seconds +is given, the debugger will wait for this long, at most a week, +before rebooting. +.Pp +.It Ic help +Print a short summary of the available commands and command +abbreviations. +.Pp +.It Ic capture on +.It Ic capture off +.It Ic capture reset +.It Ic capture status +.Nm +supports a basic output capture facility, which can be used to retrieve the +results of debugging commands from userpsace using +.Xr sysctl 2 . +.Ic capture on +enables output capture; +.Ic capture off +disables capture. +.Ic capture reset +will clear the capture buffer and disable capture. +.Ic capture status +will report current buffer use, buffer size, and disposition of output +capture. +.Pp +Userspace processes may inspect and manage +.Nm +capture state using +.Xr sysctl 8 : +.Pp +.Dv debug.ddb.capture.bufsize +may be used to query or set the current capture buffer size. +.Pp +.Dv debug.ddb.capture.maxbufsize +may be used to query the compile-time limit on the capture buffer size. +.Pp +.Dv debug.ddb.capture.bytes +may be used to query the number of bytes of output currently in the capture +buffer. +.Pp +.Dv debug.ddb.capture.data +returns the contents of the buffer as a string to an appropriately privileged +process. +.Pp +This facility is particularly useful in concert with the scripting and +.Xr textdump 4 +facilities, allowing scripted debugging output to be captured and +committed to disk as part of a textdump for later analysis. +The contents of the capture buffer may also be inspected in a kernel core dump +using +.Xr kgdb 1 . +.Pp +.It Ic run +.It Ic script +.It Ic scripts +.It Ic unscript +Run, define, list, and delete scripts. +See the +.Sx SCRIPTING +section for more information on the scripting facility. +.Pp +.It Ic textdump dump +.It Ic textdump set +.It Ic textdump status +.It Ic textdump unset +Use the +.Ic textdump dump +command to immediately perform a textdump. +More information may be found in +.Xr textdump 4 . +The +.Ic textdump set +command may be used to force the next kernel core dump to be a textdump +rather than a traditional memory dump or minidump. +.Ic textdump status +reports whether a textdump has been scheduled. +.Ic textdump unset +cancels a request to perform a textdump as the next kernel core dump. +.El +.Sh VARIABLES +The debugger accesses registers and variables as +.Li $ Ns Ar name . +Register names are as in the +.Dq Ic show Cm registers +command. +Some variables are suffixed with numbers, and may have some modifier +following a colon immediately after the variable name. +For example, register variables can have a +.Cm u +modifier to indicate user register (e.g., +.Dq Li $eax:u ) . +.Pp +Built-in variables currently supported are: +.Pp +.Bl -tag -width ".Va tabstops" -compact +.It Va radix +Input and output radix. +.It Va maxoff +Addresses are printed as +.Dq Ar symbol Ns Li + Ns Ar offset +unless +.Ar offset +is greater than +.Va maxoff . +.It Va maxwidth +The width of the displayed line. +.It Va lines +The number of lines. +It is used by the built-in pager. +.It Va tabstops +Tab stop width. +.It Va work Ns Ar xx +Work variable; +.Ar xx +can take values from 0 to 31. +.El +.Sh EXPRESSIONS +Most expression operators in C are supported except +.Ql ~ , +.Ql ^ , +and unary +.Ql & . +Special rules in +.Nm +are: +.Bl -tag -width ".No Identifiers" +.It Identifiers +The name of a symbol is translated to the value of the symbol, which +is the address of the corresponding object. +.Ql \&. +and +.Ql \&: +can be used in the identifier. +If supported by an object format dependent routine, +.Sm off +.Oo Ar filename : Oc Ar func : lineno , +.Sm on +.Oo Ar filename : Oc Ns Ar variable , +and +.Oo Ar filename : Oc Ns Ar lineno +can be accepted as a symbol. +.It Numbers +Radix is determined by the first two letters: +.Ql 0x : +hex, +.Ql 0o : +octal, +.Ql 0t : +decimal; otherwise, follow current radix. +.It Li \&. +.Va dot +.It Li + +.Va next +.It Li .. +address of the start of the last line examined. +Unlike +.Va dot +or +.Va next , +this is only changed by +.Ic examine +or +.Ic write +command. +.It Li ' +last address explicitly specified. +.It Li $ Ns Ar variable +Translated to the value of the specified variable. +It may be followed by a +.Ql \&: +and modifiers as described above. +.It Ar a Ns Li # Ns Ar b +A binary operator which rounds up the left hand side to the next +multiple of right hand side. +.It Li * Ns Ar expr +Indirection. +It may be followed by a +.Ql \&: +and modifiers as described above. +.El +.Sh SCRIPTING +.Nm +supports a basic scripting facility to allow automating tasks or responses to +specific events. +Each script consists of a list of DDB commands to be executed sequentially, +and is assigned a unique name. +Certain script names have special meaning, and will be automatically run on +various +.Nm +events if scripts by those names have been defined. +.Pp +The +.Ic script +command may be used to define a script by name. +Scripts consist of a series of +.Nm +commands separated with the +.Ql \&; +character. +For example: +.Bd -literal -offset indent +script kdb.enter.panic=bt; show pcpu +script lockinfo=show alllocks; show lockedvnods +.Ed +.Pp +The +.Ic scripts +command lists currently defined scripts. +.Pp +The +.Ic run +command execute a script by name. +For example: +.Bd -literal -offset indent +run lockinfo +.Ed +.Pp +The +.Ic unscript +command may be used to delete a script by name. +For example: +.Bd -literal -offset indent +unscript kdb.enter.panic +.Ed +.Pp +These functions may also be performed from userspace using the +.Xr ddb 8 +command. +.Pp +Certain scripts are run automatically, if defined, for specific +.Nm +events. +The follow scripts are run when various events occur: +.Bl -tag -width kdb.enter.powerfail +.It Dv kdb.enter.acpi +The kernel debugger was entered as a result of an +.Xr acpi 4 +event. +.It Dv kdb.enter.bootflags +The kernel debugger was entered at boot as a result of the debugger boot +flag being set. +.It Dv kdb.enter.break +The kernel debugger was entered as a result of a serial or console break. +.It Dv kdb.enter.cam +The kernel debugger was entered as a result of a +.Xr CAM 4 +event. +.It Dv kdb.enter.mac +The kernel debugger was entered as a result of an assertion failure in the +.Xr mac_test 4 +module of the +TrustedBSD MAC Framework. +.It Dv kdb.enter.ndis +The kernel debugger was entered as a result of an +.Xr ndis 4 +breakpoint event. +.It Dv kdb.enter.netgraph +The kernel debugger was entered as a result of a +.Xr netgraph 4 +event. +.It Dv kdb.enter.panic +.Xr panic 9 +was called. +.It Dv kdb.enter.powerfail +The kernel debugger was entered as a result of a powerfail NMI on the sparc64 +platform. +.It Dv kdb.enter.powerpc +The kernel debugger was entered as a result of an unimplemented interrupt +type on the powerpc platform. +.It Dv kdb.enter.sysctl +The kernel debugger was entered as a result of the +.Dv debug.kdb.enter +sysctl being set. +.It Dv kdb.enter.trapsig +The kernel debugger was entered as a result of a trapsig event on the sparc64 +platform. +.It Dv kdb.enter.unionfs +The kernel debugger was entered as a result of an assertion failure in the +union file system. +.It Dv kdb.enter.unknown +The kernel debugger was entered, but no reason has been set. +.It Dv kdb.enter.vfslock +The kernel debugger was entered as a result of a VFS lock violation. +.It Dv kdb.enter.watchdog +The kernel debugger was entered as a result of a watchdog firing. +.It Dv kdb.enter.witness +The kernel debugger was entered as a result of a +.Xr witness 4 +violation. +.El +.Pp +In the event that none of these scripts is found, +.Nm +will attempt to execute a default script: +.Bl -tag -width kdb.enter.powerfail +.It Dv kdb.enter.default +The kernel debugger was entered, but a script exactly matching the reason for +entering was not defined. +This can be used as a catch-all to handle cases not specifically of interest; +for example, +.Dv kdb.enter.witness +might be defined to have special handling, and +.Dv kdb.enter.default +might be defined to simply panic and reboot. +.El +.Sh HINTS +On machines with an ISA expansion bus, a simple NMI generation card can be +constructed by connecting a push button between the A01 and B01 (CHCHK# and +GND) card fingers. +Momentarily shorting these two fingers together may cause the bridge chipset to +generate an NMI, which causes the kernel to pass control to +.Nm . +Some bridge chipsets do not generate a NMI on CHCHK#, so your mileage may vary. +The NMI allows one to break into the debugger on a wedged machine to +diagnose problems. +Other bus' bridge chipsets may be able to generate NMI using bus specific +methods. +.Sh FILES +Header files mention in this manual page can be found below +.Pa /usr/include +directory. +.Pp +.Bl -dash -compact +.It +.Pa sys/buf.h +.It +.Pa sys/domain.h +.It +.Pa netinet/in_pcb.h +.It +.Pa sys/socket.h +.It +.Pa sys/vnode.h +.El +.Sh SEE ALSO +.Xr gdb 1 , +.Xr kgdb 1 , +.Xr acpi 4 , +.Xr CAM 4 , +.Xr mac_test 4 , +.Xr ndis 4 , +.Xr netgraph 4 , +.Xr textdump 4 , +.Xr witness 4 , +.Xr ddb 8 , +.Xr sysctl 8 , +.Xr panic 9 +.Sh HISTORY +The +.Nm +debugger was developed for Mach, and ported to +.Bx 386 0.1 . +This manual page translated from +.Xr man 7 +macros by +.An Garrett Wollman . +.Pp +.An Robert N. M. Watson +added support for +.Nm +output capture, +.Xr textdump 4 +and scripting in +.Fx 7.1 . |
